Most modern automotive fuel systems utilize fuel injectors to provide precise metering of fuel for introduction towards each combustion chamber. Additionally, the fuel injector atomizes the fuel during injection, breaking the fuel into a large number of very small particles, increasing the surface area of the fuel being injected, and allowing the oxidizer, typically ambient air, to more thoroughly mix with the fuel prior to combustion. The metering and atomization of the fuel reduces combustion emissions and increases the fuel efficiency of the engine. Thus, as a general rule, the greater the precision in metering and targeting of the fuel and the greater the atomization of the fuel, the lower the emissions with greater fuel efficiency.
An electromagnetic fuel injector typically utilizes a solenoid assembly to supply an actuating force to a fuel metering assembly. Typically, the fuel metering assembly is a plunger-style closure member which reciprocates between a closed position, where the closure member is seated in a seat to prevent fuel from escaping through a metering orifice into the combustion chamber, and an open position, where the closure member is lifted from the seat, allowing fuel to discharge through the metering orifice for introduction into the combustion chamber.
The fuel injector is typically mounted upstream of the intake valve in the intake manifold or proximate a cylinder head. As the intake valve opens on an intake port of the cylinder, fuel is sprayed towards the intake port. In one situation, it may be desirable to target the fuel spray at the intake valve head or stem while in another situation, it may be desirable to target the fuel spray at the intake port instead of at the intake valve. In both situations, the targeting of the fuel spray can be affected by the spray or cone pattern. Where the cone pattern has a large divergent cone shape, the fuel sprayed may impact on a surface of the intake port rather than towards its intended target. Conversely, where the cone pattern has a narrow divergence, the fuel may not atomize and may even recombine into a liquid stream. In either case, incomplete combustion may result, leading to an increase in undesirable exhaust emissions.
Complicating the requirements for targeting and spray pattern is cylinder head configuration, intake geometry and intake port specific to each engine""s design. As a result, a fuel injector designed for a specified cone pattern and targeting of the fuel spray may work extremely well in one type of engine configuration but may present emissions and driveability issues upon installation in a different type of engine configuration. Additionally, as more and more vehicles are produced using various configurations of engines (for example: inline-4, inline-6, V-6, V-8, V-12, W-8 etc.,), emission standards have become stricter, leading to tighter metering, spray targeting and spray or cone pattern requirements of the fuel injector for each engine configuration.
It is believed that known metering orifices formed at an angle with respect to a longitudinal axis (i.e., xe2x80x9cangled metering orificesxe2x80x9d) of a fuel injector and arrayed in circular pattern along the longitudinal axis allow greater symmetry and greater latitude in configuring the fuel injector to operate with different engine configuration while achieving an acceptable level of fuel atomization, (quantifiable as an average Sauter-Mean-Diameter (SMD)). It is believed, however, that angled metering orifices require, at the present time, specialized machinery, trained operators and greater inefficiencies to manufacture than non-angled metering orifices. Moreover, even if the angled metering orifices can be competitively produced with the non-angled metering orifices, the angled metering orifices may still have uneven fuel distribution.
It would be beneficial to develop a fuel injector in which non-angled metering orifices can be used in controlling spray targeting and spray distribution of fuel. It would also be beneficial to develop a fuel injector in which increased atomization or precise targeting can be changed so as to meet a particular fuel targeting and cone pattern from one type of engine configuration to another type.
The present invention provides fuel targeting and fuel spray distribution at an acceptable level of fuel atomization with non-angled metering orifices. The present invention allows a fuel spray pattern of an injector to approximate a flow area downstream of the fuel injector so that regardless of a rotational orientation of the fuel injector about the longitudinal axis, the flow area can be achieved. In a preferred embodiment, a fuel injector is provided. The fuel injector includes a housing, a seat, a closure member and a metering disc. The housing has passageway extending between an inlet and an outlet along a longitudinal axis. The seat has a sealing surface facing the inlet and forming a seat orifice with a terminal seat surface spaced from the sealing surface and facing the outlet, and a first channel surface generally oblique to the longitudinal axis and is disposed between the seat orifice and the terminal seat surface. The closure member is disposed in the passageway and contiguous to the sealing surface so as to generally preclude fuel flow through the seat orifice in one position. The closure member is disposed in the passageway and contiguous to the sealing surface so as to generally preclude fuel flow through the seat orifice in one position. A magnetic actuator is disposed proximate the closure member so that, when energized, the actuator positions the closure member away from the sealing surface of the seat so as to allow fuel flow through the passageway and past the closure member. The metering disc is proximate to the seat and includes a second channel surface confronting the first channel surface so as to form a flow channel. The metering disc has at least two metering orifices located outside of the first virtual circle. The at least two metering orifices being located about the longitudinal axis at substantially equal arcuate distance apart between adjacent metering orifices. Each metering orifice extends generally parallel to the longitudinal axis between the second channel surface and a outer surface spaced from the second channel surface so that, when the magnetic actuator is energized to move the closure member, a flow of fuel through the metering orifices generates a spray pattern that intersects a virtual plane orthogonal to the longitudinal axis with a flow area having a plurality of different radii, one of the radii of the flow area including a maximum radius that, when rotated about the longitudinal axis, defines a circular area larger than a portion covered by the flow area such that targeting of the spray pattern requires orientation of the metering orifices about the longitudinal axis.
In yet another aspect of the present invention, a method of targeting a fuel flow area about a longitudinal axis is provided. The fuel injector includes a passageway extending between an inlet and outlet along a longitudinal axis, a seat and a metering disc. The seat has a sealing surface facing the inlet and forming a seat orifice. The seat has a terminal seat surface spaced from the sealing surface and facing the outlet, and a first channel surface generally oblique to the longitudinal axis and disposed between the seat orifice and the terminal seat surface. The closure member is disposed in the passageway and contiguous to the sealing surface so as to generally preclude fuel flow through the seat orifice in one position and disposed in another position spaced from the sealing surface to permit fuel flow through the passageway through the seat orifice. The metering disc has at least two metering orifices. Each metering orifice extends between second and outer surfaces along the longitudinal axis with the second surface facing the first channel surface. The method can be achieved, in part, by locating the at least two metering orifices outside of the first virtual circle, the metering orifices extending generally parallel to the longitudinal axis through the second and outer surfaces of the metering disc; flowing fuel through the at least two metering orifices upon actuation of the fuel injector so that a fuel flow path intersecting a virtual plane orthogonal to the longitudinal axis defines a flow area having a plurality of different radii about the longitudinal axis, one of the radii including a maximum radius that, when rotated about the longitudinal axis, defines a circular area larger than the flow area; and orientating the flow area about the longitudinal axis so as to adjust a targeting of the flow area towards a different portion of the circular area.